Amar Mandhyan, Director- Technical Sales, Mobility Solutions, CommScope Asia Pacific
Global mobile traffic has been growing at over 50% per annum for many years. This puts huge capacity demand on the 4G networks without proportional revenue growth for the operators, due to intense competition and launch of new offerings.
This rising data demand will continue to underline the 5G Networks. Mobile video will generate much of the projected network traffic growth. In the IoT, a multitude of sensors, meters and other machines will add to the data load put onto wireless networks and will further push the need for more capacity and more ubiquitous coverage.
This means that operators must be pragmatic with their network investments by re-looking at their network models and optimizing available resources to bring about maximum efficiencies.
Below are some of the key recommended focus areas for the operators for 5G introduction:
Upgrade to Gigabit LTE
5G Networks will not provide ubiquitous coverage during initial few years of rollout. As per some industry estimates, 5G Networks will reach 40% population coverage, while 4G Networks will reach 90% population coverage in next five years. Initial 5G rollout will be in Cities and Traffic hot spots. However, subscribers will still expect 5G like experience, even when they move out of 5G coverage and move into 4G coverage. This means that 4G networks will need to be upgraded with features like 4×4 MIMO, 256 QAM and Carrier Aggregation, along with introduction of additional spectrum through re-farming of existing 2G/3G bands and use of new licensed and unlicensed bands. New 4G devices supporting ~1 Gbps speeds are already available, and soon device support for ~2Gbps speeds will also be there.
Figure-1 shows the number of operators who have deployed/planned the three advanced 4G features required for Gigabit LTE (GSA, Nov 2018). Very few Operators are investing in all the three functionalities. So, there is still a long way to go.
As per 3GPP R15 Standards, 4G Networks will be integral part of functioning of 5G Networks as part of Non-Standalone (NSA) Architecture for 5G. 4G RAN will anchor the Control Plane and 5G RAN will be used in Dual Connectivity (DC) mode with 4G RAN for User Plane traffic. This may require end to end upgrade of 4G Networks for inter-operability with 5G Networks and also to enhance capacity.
Virtualization with Open Interfaces
Most 4G RAN Networks are deployed with Baseband Unit (BBU) and Remote Radio Unit (RRU) co-located at the site. With virtualized RAN (vRAN), BBUs run on General Purpose Hardware in Data Centers, which could be located hundreds of kilometers away, and controlling many RRUs. The total cost of ownership (TCO) for such architecture will be significantly lower due to lower cost of BBU Hardware, pooling benefits of a Centralized BBU and reduced maintenance costs, while at the same time providing flexibility of dynamic scaling of resources to meet varying traffic demands in the network.
5G vRAN Networks can be further innovated by use of open interfaces between 5G RAN building blocks Central Unit (CU), Distributed Unit(DU) and Radio Unit (RU) and use of open Application Programming Interfaces (APIs) to these functional blocks. Open interfaces will further reduce cost, avoid vendor lock-in, promote innovation through use of Machine Learning and Artificial Intelligence, and optimize RAN Hardware resources by enabling productive use of excess inventory of different RAN vendors.
Pilot programs using open interfaces are already underway. Industry bodies like ORAN, TIP, IEEE and others are working towards this cause, led by a cross-section of Global Operators.
Optimum Antenna Solutions
A big part of capacity promise of 5G is due to the use of Massive MIMO technology, which proposes to increase site capacity by more than 3 times, as compared to 4×4 MIMO. While Massive MIMO in mmWave is inherently necessary for coverage reasons (apart from capacity benefits), it’s implicit use in sub-6 GHz Networks is not needed. The size of Massive MIMO antenna is proportional to the wavelength. So, for sub 6 GHz bands, these antennas are larger, heavier and need large power to be carried up the tower to the Antennas through thicker power trunks. These infrastructure requirements and additional tower loading may limit its use to the ‘most needed’ sites only. Operators must also evaluate the cost-performance benefits of Massive MIMO, as compared to some of the other capacity solutions like Multi-Beam Antennas, Passive Beamforming Antennas, Radios Blind Mated to Antennas etc.
An example of a hybrid beamforming antenna for a typical 5G Site co-located with existing 2G/3G/4G site with all popular bands is shown in Figure-3.
Each site is unique in terms of terrain, indoor and outdoor traffic distribution, Coverage, SINR distribution,and deployed spectrum assets. An appropriate RF Path solution, considering all factors, will add required capacity at lowest possible cost.
Fiber to Sites and Fiber Network Convergence
Increased 5G site capacity and upgrade of 4G networks to Gigabit LTE means that the fronthaul and backhaul transport networks also need to upgrade. Many operators are still in the range of 20% to 30% 4G sites with fiber based backhaul, which will not be sufficient for 5G Networks.
Fiber network convergence refers to the combination of multiple services within a single access network. This is where a single pipe is used to deliver all or multiple forms of communication services over a single fiber network. For example, operators that have an existing fiber-to-the-home (FTTH) or fiber-to-the-building (FTTB) network is perfect for supporting fast-growing mobile applications such as distributed antenna system (DAS), small cell and Wi-Fi backhaul, Centralized 4G and 5G RAN fronthaul and backhaul. Through fiber network convergence, a service provider can deliver a wider range of services, adopt new business models, offer innovative services and enter new markets.
Metro Cell Antennas
A significant trend in 5G will be locating cell sites on city streets and urban areas in the form of Metro Cells, which add localized capacity to address the growing data traffic needs. Figure below shows an example of a Gigabit Antenna that can provide very high capacity for 4G and 5G Networks, by enabling deployment of 4×4 MIMO at typical 4G and 5G licensed bands, and also exploiting the unlicensed bands.
Choosing the right small cell antenna solution can reduce the total number of sites required in a hot zone. The right antennas, while increasing network capacity also makes it future proof by enabling addition of new spectrum easily in the same antenna. It also empowers site sharing between operators through independent use of Antenna ports and Remote Electrical tilts. The Remote Electrical Tilt feature, which is usually not found in integrated Antenna designs of Metro Cells, is a powerful tool to provide effective interference control from the Macro Network signals.
In summary, while 5G promises a lot of exciting things, it’s business case for operators depends on decisions that enable optimal use of new and existing resources. Some key suggestions have been highlighted above for laying a solid foundation for 5G networks.